The present invention generally relates to enhancements in devices for filtering and separating liquids. More particularly, the present invention relates to fuel filters for removing foreign particles and separating water from fuel of a fuel supply system associated with an internal combustion engine.
Diesel fuel supplies frequently contain significant quantities of abrasive particles and water which present the potential for permanent damage to the components of the fuel injection pump and the fuel delivery system of the engine. Consequently, an effective fuel filter assembly is a practical necessity and is conventionally incorporated into the fuel supply system of a diesel engine. A multitude of conventional fuel filter assemblies employ a disposable filter cartridge which is replaced at pre-established intervals of filter usage. Such filter cartridges typically perform the dual function of removing particulate material from the diesel fuel and separating water from the fuel.
The fuel filter assemblies to which the present invention relates include a replaceable filter cartridge and a header with a base which accepts the disposable filter cartridge. The filter cartridge has a housing which defines an axial opening at one end thereof to provide fuel communication between the fuel delivery system and a filter element disposed within the cartridge housing. A sealing grommet is disposed at the axial opening to provide a fluid-tight seal. The fuel filter cartridges may house a single stage filter or a dual stage filter and may assume a wide variety of shapes and configurations.
In conventional fuel filter assemblies to which the invention relates, a manual primer mechanism is often provided to facilitate engine starting after a spent fuel cartridge has been replaced with a fresh one. In particular, this fuel primer mechanism is disposed in the fuel flow path between the fuel entry port and the central fuel conduit such that actuation of the manual primer pump draws fuel from the connected fuel supply and forces it through the filter cartridge and into the fuel injection pump. While such designs can effectively prime the filter cartridge, they suffer from the deficiency that the pressure pulses generated by the primer mechanism push the air which is trapped in the fuel filter assembly into the fuel supply system. This air is carried by the fuel to the fuel injection pump where it interferes with the proper operation of the fuel injection pump and may have a deleterious effect on emissions.
Conventional fuel filter assemblies have employed a number of approaches to reduce or eliminate the pressure pulse associated with operation of the primer mechanism. One conventional primer pump system employs a manually operated valve. However, such prior approaches have generally reduced the effectiveness of the hand primer mechanism in removing the trapped air. Accordingly, there is a need in the art for improved fuel filter assemblies and methods therefor in which the fuel filter assembly may be primed without transporting a portion of the air contained therein to the fuel injection pump.